Diazotype photoprinting material



Patented Apr. 22, 1952 DIAZOTYPE PHOTOPRINTING MATERIAL Saul R. Buc, Northampton County, Pa., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application November 23, 1948, Serial No. 61,727

7 Claims.

This invention relates to diazotype photoprinting material and process for the manufacture thereof. More particularly, this invention relates to diazotype photoprinting material having a two-component diazotype light sensitive layer and a method for making the same.

Two-component diazotype light sensitive layers contain a light sensitive diazo compound, suitably stabilized against premature coupling prior to development of the material, together with an azo coupling component. Upon exposure of such a layer to light of locally varied intensity in accordance with an original pattern or design to be reproduced, the diazo compound is partly or completely destroyed in the light exposed portions, so that upon subjecting the layer .to developing treatment as by exposure to alkaline vapors, e. g. ammonia, or treatment with an alkaline solution, the residual diazo compound couples with the azo component to form an azo dye image of the original pattern. The development is conveniently carried out in the dry process by exposing the layer to ammonia or a volatile amine, or by the wet or semi-wet process in which an alkaline developer solution is applied to the layer after exposure thereof.

To manufacture two-component diazotype layers, the sensitizing components are generally applied or deposited successively or in combination on a support such as paper, plastic materials, metals, glass or the like. For absorbent materials like paper, the sensitizing composition can be used in aqueous solution, while for plastics it has been suggested to use a solution containing an organic solvent which has a solvent or swelling action upon the plastic support.

Many of the sensitizing materials heretofore employed in two-component layers were defective in that the image lacked fastness to water and aqueous solutions because of the solubility in water of the resulting azo dye. Moreover, when incorporated in a plastic carrier, the azo dye produced on development was subject to migration or offsetting in the layer. Both of these conditions cause blurring of the image, rendering such compositions unsuitable for prints in which sharpness of the image is required.

At the same time it is desirable to use sensitizing components in diazotype layers which yield dark shades adapted to reproduce the opaque parts of the original, While at the same timehaving a sufficiently moderate gradation to reproduce a wide range of densities as are generally found in photographs.

Diazotype images produced with two-component layers containing resorcinol as a coupler are subject to disadvantages. When such images are formed on a plastic base, the image is subject to migration or ofisetting, causing blurring or spreading of the lines and. margins of the image. The colorations produced are not fast to washing and hence often yield a blurred image when the development is carried out by the wet or semi-wet process. The brown colorations ordinarily obtained with resorcinol have a definite reddish tint which is not desirable, especially in photographic reproductions.

It is an object of this invention to provide novel two-component diazotype layers which yield dark purplish-brown images having a wide range of gradation suitable for the reproduction of photographic originals, which are not subject to ofisetting or migration when produced on plastic carriers, and having good fastness to water and aqueous solutions.

I have discovered that diazotype layers containing, as the azo coupling component, a crystalline tetrameric condensation product of a m-polyhydric phenol (resorcin-ol, phloroglucinol) with an equimolecular amount of an aldehyde having the formula RCHO, wherein R is a hydrocarbon radical of l-6 carbon atoms, yield prints having dark purplish brown images of good fastness to light which do not offset or migrate in a plastic carrier and which have excellent fastness to water and aqueous solutions.

The azo coupling components employed in accordance with this invention can be conveniently prepared, by the procedure of Niederl et al. in J. A. C. S. 62 (1940), p 2512-2513, by mixing 1 mol of resorcinol or phloroglucinol with 0.9-1 mol of a hydrocarbon aldehyde, wherein the hydrocarbon contains 1-6 carbon atoms, in aqueous or aqueous alcoholic sulfuric acid of 5-10% concentration, and allowing the reaction mixture to stand without external heating until the crystalline condensation product separates. For lower aldehydes, water can be used, while for aldehydes containing 4 or more carbon atoms, equal parts by weight of ethyl alcohol and water are employed as a reaction medium to retain the aldehyde solution; The concentration of the aldehyde and m-polyhydric phenol in the reaction mixture is generally 2-7%, the reaction being carried out by dissolving the m-polyhydric phenol in a portion of aqueous or aqueous alcoholic sulfuric acid, dissolving the aldehyde in the remainder of the reaction medium, and gradually adding the aldehyde solution to the m-polyhydric phenol solution. The crystalline condensation product which separates from the The products thus obtained 3 4 from resorcinol, as given by Niederl et al., is as compounds against premature coupling and defollows; composition comprise organic acids such as for- OH R (])H mic, citric, tartaric, mellitic, and sulfosalicylic acids; anti-oxidants such as thiourea, and stabi- 5 lizing salts such as zinc chloride or other halides forming complex addition products with the diazo salts, e. g. boron trifluoride. Colloidal wetting 2: agents such as saponine are likewise advantal H geously included.

My invention will be more fully understood 011 from the following examples wherein the parts are by weight unless otherwise indicated.

1 (5 Example 1 OH H 4 grams of tetrameric crystalline condensa- R being the hydrocarbon radical of the aldetion product of equimolecular amounts of acetalhyde. However, it is believed th structure may dehyde and resorcinol were dissolved in 100 cc. be of the open-chain type as follows: of ethyl alcohol, and the resulting solution coated i R R-onoH- -CH 5H--' t11- HO- OH HO- -o11 HO- OH HO- -on R having the same significance as above. Coron paper, After drying, the paper was coated responding derivatives of phloroglucinol have an with a solution of the following composition: additional hydroxyl group in the benzene rings in m-position to the other hydroxyl groups.

In preparing diazotype photoprinting material containing the crystalline tetra-meric condensation products described above, the latter may be applied simultaneously or successively with a light sensitive diazo compound, suitably stabilized a against premature coupling to a base or 3 gl-diethyilamrnobcnzene dlaZOI'lllllTl chloride port. The products are applied in solvents adaptn 2 douo e Sal ed for impregnation of the carrier. Thus, al- 40 diluted with water to avolume of 100 cc.

1 cc. isopropanol 5 cc. ethylene glycol 5 g. citric acid 5 g. zinc chloride 5 g. thiourea 0.1 g. saponine cohols (ethanol, methanol, isopropanol) are suit- After drying, the resulting sensitized material able as solvents for applying the coupling comwas exposed under an original pattern to be reponents to paper and other absorbent carriers. produced, such as an opaque line drawing on a When plastic materials such as a cellulose ester translucent background or a photographic diaor ether, e. g. cellulose acetate of ether cellulose, 7 positive, and thereafter developed by exposure to or a resinous polymer, such as polyvinyl alcohol ammonia. Asharp purplish-brown image was obor other polyvinyl resins, are employed as cartained of excellent fastness to light, of deeper riers, a solvent mixture is preferably employed shade, and better fastness to washing than an imfor applying the coupling components, said mixage produced with a sensitizing composition simiture having a swelling or slight solvent action on lar to that described herein but containing rethe plastic carrier employed. For example, solusorcinol instead of the acetaldehyde resorcinol tions containing 'y-valerolactone in aqueous alcocondensation product. holic medium (containing for example, methanol, Exam Z6 2 ethanol, isopropanol and butanol) can be adva'np tageously used for impregnating cellulose acetate. A sensitizing solution was prepared having the Since the coupling components of this invenfollowin composition: tion are water-insoluble or of low solubility in water, an alcoholic solution thereof can be first applied to an absorbent base such as paper, and the light sensitive diazo component, together with stabilizers, anti-oxidants and the like, subse- 6 quently applied in aqueous solution to the same base after evaporating the alcoholic solution. When a mixed solvent is employed, adapted to dissolve both the coupling component and the light sensitive diazo compound, such a solution can be used to sensitize a base in a single operation.

The light sensitive diazo compounds are preferably diazotized diamines of the benzene series, The resulting solution was heated to about 50 C. particularly those having at least one substituent and coated at this temperature on cellulose ace- 50 parts water 20 parts isopropyl alcohol 1 part zinc chloride 2 parts thiourea 10 parts 'y-valerolactone 5 parts sulfosalicylic acid 5 parts formic acid 5 parts butanol 4 parts p-diethylamino-2-methyl benzene diazonium chloride ZI1C12 double salt; and 6 parts of the resorcinol acetaldehyde tetrai'neric condensation product of Example 1.

on one of the amino groups. Diazotized o-aminotate foil and on plastic coated paper. The modnaphthols are also adapted for use at light senerately elevated temperature was employed to sitive diazo compounds in the two-component maintain all of the components of the sensitizing layers of the invention. mixture in solution. After drying, copies were Additional ingredients for stabilizing the diazo made by the procedure described in Example 1.

Development can be eifected either with ammonia or with an aqueous alkalin solution such as aqueous ammonia, sodium carbonate, tri-sodium phosphate, or tri-ethanolamine.

The resulting image was likewise of dark purplish-brown color, of excellent sharpness showing no migration or ofisetting and of excellent fastness to light. A print obtained with diazotype material prepared in the same manner as described in this example but using resorcinol instead of the acetaldehyde resorcinol condensation product, showed substantial migration and ofisetting and had a much lighter color.

Instead of the resorcinol acetaldehyde condensation product of the foregoing examples, there can be employed the corresponding crystalline tetrameric equirnolecular condensation product of acetaldehyde with pholorglucinol, or of propionaldehyde, butyraldehyde, isobutyraldehyde, hexaldehyde, or benzaldehyde with either resorcinol or pholorogiucinol, whereby images having similarly advantageous properties are obtained.

Instead of the light sensitive diazo compounds disclosed in the examples, there can be used the diazo compounds of p-ethylamino m-toluidene, p amino N diethyl m-toluidene, p-amino-N- methylaniline, p-amino Z-methoxy-N-cyclohexylaniline, p-amino N 2' hydroxyethylaniline, p-amino N ethyl-N-Z-hydroxyethylaniline, 3 aminocarbazole, 1,2-, 2,1-, or 1,4-aminonaphthol, 1,2-aminonaphthol-e-sulfonic acid, or 2,1-aminonaphthol-3,6-disulfo acid. These diazo compounds can be employed in the form of their diazonium chloride zinc chloride double salts or the corresponding boron trifluoride complex addition products.

As disclosed in the examples, alcohols such as methanol, ethanol, isopropanol and butanol can be employed as media for impregnating absorbent bases with the aldehyde polyhydric phenol condensation products of this invention, particularly when applied separately from the light sensitive diazo component, and mixed solvents containing water, alcohols and a softening agent for plastics such as 'y-valerolactone, can be used as a medium for applying the light sensitive diazo component as well as coupling components of this invention in a single operation to a plastic support.

Variations and modifications which will be ob- Vious to those skilled in the art can be made in this invention without departing from the scope thereof.

I claim:

1. Diazotype photoprinting material, comprising in a light sensitive layer, a light sensitive diazo component, and as a coupling component, a crystalline tetrameric condensation product of a m-polyhydric phenol with an equimolecular amount of an aldehyde having the formula RCHO, wherein R is a hydrocarbon radical having 1-6 carbon atoms.

2. Diazotype photoprinting material, comprising a plastic base impregnated with a light sensitive diazo component and with a coupling component which is a crystalline tetrameric condensation product of a m--polyhydric phenol with an equimolecular amount of an aldehyde having the formula RCHO, wherein R is a hydrocarbon radical having l6 carbon atoms.

3. Diazotype photoprinting material, comprising in a light sensitive layer, a light sensitive diazotized p-diamine of the benzene series, and as a coupling component, a crystalline tetrameric c0ndensation product or" resorcinol with an equimolecular amount of acetaldehyde.

4. Diazotype photoprinting material, comprising a paper case impregnated with the crystalline tetrameric condensation product of resorcinol with an equimolecular amount of acetaldehyde, and with the zinc chloride double salt of p-diethylaminobenzene diazonium chloride.

5. Diazotype photoprinting material, comprising a plastic layer impregnated with the crystalline tetrameric condensation product of resorcinol with an equimolecular amount of acetaldehyde, and With the zinc chloride double salt of p diethylamino 2 methyl benzene diaz'onium chloride.

6. A process for the manufacture of light sensitive diazotype materials, which comprises impregnating an absorbent base with an alcoholic solution of the crystalline tetrameric condensation product of resorcinol with an equimolecular amount of acetaldehyde, drying the base, and impregnating the latter with an aqueous solution containing the zinc chloride double salt of pdiethylaminobenzene diazonium chloride.

'7. A process for the manufacture of light sensitive diazotype materials, which comprises impregnating a plastic base with an aqueous alcoholic solution containing -valerolactone, of the crystalline tetrameric condensation product of resorcinol with an equimolecular amount of acetaldehyde, and containing the zinc chloride double salt of p-diethylamino-Z-methyl benzene diazonium chloride.

SAUL R. BUC.

REFERENCES CITED FOREIGN PATENTS Country Date Great Britain Aug. 26, 1938 Number 

1. DIAZOTYPE PHOTOPRINTING MATERIAL, COMPRISING IN A LIGHT SENSITIVE LAYER, A LIGHT SENSITIVE DIAZO COMPONENT, AND AS A COUPLING COMPONENT, A CRYSTALLINE TETRAMERIC CONDENSATION PRODUCT OF A M-POLYHYDRIC PHENOL WITH AN EQUIMOLECULAR AMOUNT OF AN ALDEHYDE HAVING THE FORMULA RCHO, WHEREIN R IS A HYDROCARBON RADICAL HAVING 1-6 CARBON ATOMS. 